Global Simulation Model Research Articles

Forward Dynamics Analysis of the 6-PUS Mechanism Based on Platform-Legs Composite Simulation

The dynamics analysis plays an important role for the control,simulation and optimization of the parallel manipulators. Normally,the Stewart type manipulators have a platform and several legs. The inverse dynamics can be solved efficiently by taking the advantage of such structural characteristics. However,for the forward dynamics analysis,this structural decomposition still faces challenges from both modeling and computation. In this paper,an efficient approach is proposed for the forward dynamics of the 6-PUS manipulator based on the platform-legs composite simulation. By composite method,the dynamics modeling of the parallel manipulator is separated into the forward dynamics of the platform and the kineto-statics of the legs. The global simulation model can be constructed by connecting the predefined platform model and leg models according to the manipulator's topology. Thus,the global simulation can be decomposed into the independent calculations of purely algebraic equations and ordinary differential equations (ODEs),the computational cost can be reduced and the stability of the simulation can be improved. For the purpose of solving the manipulator's forward dynamics accurately,the algebraic-loop problem is discussed and a closed form algorithm is proposed. A numerical example of the 6-PUS manipulator is given to demonstrate the effectiveness of the proposed approach. The example results show that the modeling efficiency can be improved and the simulation stability can be ensured for decomposing the system equations into purely algebraic equations and ODEs.

Economic Growth and Income Distribution: Linking Macro- economic Models with Household Survey Data at the Global Level

This paper describes in detail the analytical structure of the Global Income Distribution Dynamics (GIDD) model, a global macro-micro modelling framework, and provides some examples of its recent applications. GIDD is the first macro-micro global simulation model focused on long-term, global growth and distribution dynamics. GIDD has been applied in analyzing the effects of multilateral trade liberalization or mitigation of climate change damages, among others. It also explicitly considers long term time horizons during which changes in the demographic structure are crucial components of both growth and distribution dynamics. The challenges of assessing plausible worldwide distributional implications of growth, large shocks, and policy changes are daunting. Although addressing these issues in a macro-micro framework is subject to great uncertainty, a clearly superior alternative is not yet available.

GSIM Measurement of the Effects of the EU accession of the Balkans and Turkey on Agricultural Trade

GSIM Measurement of the Effects of the EU accession of the Balkans and Turkey on Agricultural Trade In this paper, the global simulation model (GSIM) for the analysis of global, regional, and unilateral trade policy changes by Francois and Hall (2003) was applied to the agricultural trade between the EU, the Balkans and Turkey. This was done in order to measure the effects of an EU accession of the Balkans and Turkey. Most of the changes in welfare after a full liberalisation of agricultural trade between the Balkans and Turkey on the one hand and the EU on the other hand can be expected in the accession countries themselves. It is estimated that incumbent EU members will be affected only to a minor extent. It was also estimated that the exchange rate risk is not very high.

Bow shock contributions to region 1 field‐aligned current: A new result from global MHD simulations

We present a new result, based on a global MHD simulation model, that the bow shock contributes significantly to the region 1 field‐aligned current (FAC) under strong southward interplanetary magnetic field conditions. More than 50 percent of the total region 1 FAC may originate from the bow shock in certain circumstances. Stronger southward interplanetary magnetic field, higher solar wind speed, or larger ionospheric Pedersen conductance, leads to greater contribution from the bow shock to the region 1 current. This new result quantifies the interaction between the bow shock and the ionosphere through the region 1 current. The methodology presented in the present paper should be applicable to quantify the bow shock contributions to the substorms through the region 1 current, as well as to the magnetic storms through the ring current and the region 2 current, leading to understanding the space weather as magnetic storms in the solar‐terrestrial environment.

Optimization of the design of a crucible for a SiC sublimation growth system using a global model

Induction heating, temperature field and growth rate for a sublimation growth system of silicon carbide were calculated by using a global simulation model. The effects of shape of the crucible on temperature distribution and growth rate were investigated. It was found that thickness of the substrate holder, distance between the powder and substrate, and angle between the crucible wall and powder free surface are important for growth rate and crystal quality. Finally, a curved powder free surface was also studied. The results indicate that the use of a curved powder free surface is also an effective method for obtaining a higher growth rate.

Continuous reconnection line and pressure‐dependent energy conversion on the magnetopause in a global MHD model

We present results on magnetopause reconnection processes in the Gumics‐4 global MHD simulation model. The reconnection line on the magnetopause is identified using a topological method, and its behavior as a function of the interplanetary magnetic field (IMF) direction is shown to be consistent with the component reconnection hypothesis. Energy conversion associated with reconnection is quantified using integrals of Poynting vector divergence. The efficiency of energy conversion depends on both the IMF direction and the solar wind dynamic pressure. We vary the solar wind speed and density separately and show that while both affect the appearance of magnetopause processes, speed has a much stronger effect on the total reconnection efficiency.

Numerical investigation of induction heating and heat transfer in a SiC growth system

AbstractA global simulation model is applied for a silicon carbide growth system heated by induction coils. A finite‐volume method (FVM) and a global model are applied to solve the equations for electromagnetic field, conductive and radiative heat transfer. The growth rate is predicted by Hertz‐Knudsen equation and one‐dimensional mass transfer equation. Further, simulations for five different coil positions are carried out to investigate the effects of coil position on temperature distribution in the furnace. The numerical results reveal that the variation of temperature in the radial direction along the substrate surface and the temperature difference between the powder and substrate are greatly affected by the coil position. The predicted growth rate along the substrate surface for five coil positions is also studied. Finally, a reasonable range of coil positions maintaining a balance between large‐diameter crystal, high growth rate, temperature limitation of material and lower electrical power consumption is obtained. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The impact of climate change on tourism in Germany, the UK and Ireland: a simulation study

We downscale the results of a global tourism simulation model at a national resolution to a regional resolution. We use this to investigate the impact of climate change on the regions of Germany, Ireland and the UK. Because of climate change, tourists from all three countries would spend more holidays in the home country. In all three countries, climate change would first reduce the number of international arrivals—as Western European international tourist demand falls—but later increase numbers—as tourism demand from increasingly rich tropical countries grows. In Ireland and the UK, the regional pattern of demand shifts is similar to the international one: tourism shifts north. In Germany, the opposite pattern is observed as the continental interior warms faster than the coast: tourism shifts south.

Generic discrete–continuous simulation model for accurate validation in heterogeneous systems design

Heterogeneous systems combining several technologies will potentially overcome several performances and applicability limitations, as well as providing new useful features. However, their design is currently confronted to important challenges. One of the key challenges is the integration of pre-built components specific to different application domains (e.g. electrical, mechanical, optical, etc.). In this context, new CAD tools are mandatory to offer a global view of the designed systems and to enable their overall validation. This paper presents a generic discrete–continuous simulation model for an accurate global validation in heterogeneous systems design. This model enables to use powerful tools for the discrete and continuous domains. Solutions are proposed for model's layers implementation in the case of SystemC and Simulink simulators. The continuous–discrete simulation tool is proposed. This tool integrates the two previous simulators by automatically generating global simulation model instances. The evaluation of the simulation model was performed using an illustrative application.

Hybrid simulation study of ion escape at Titan for different orbital positions

Titan, the largest moon of Saturn, forms a unique plasma interaction with the Kronian corotating plasma. Titan’s dense and nitrogen rich atmosphere is the primary source of the nitrogen torus around Titan’s orbit through the subsonic and super-Alfvénic interaction between the corotating plasma of the Kronian system and the exosphere and ionosphere of Titan. We have studied this magnetic interaction of Titan with a global hybrid simulation model and especially the effect of the orbital position of Titan with four different Saturn local time. The hybrid simulation includes the various drifts important in Titan’s plasma environment. Under the assumption of uniform magnetospheric properties along Titan’s orbit, differences were found in the tail structure while the net emission rates varied only little. For all four studied orbital positions the magnetic field maximum was located on the anti-Saturn side of Titan. The iono- and magnetotails were co-aligned and tilted towards Saturn up to 45°.

微視的乱流シミュレーション ４．微視的乱流シミュレーションにおける将来に向けての課題

Prospects of the microturbulence simulation study for the magnetic confinement fusion are described forclosing the Lecture Note. Key issues in constructing a global simulation model of the turbulent transport as well as subjects relating to multi-scale and multi-physics problems are discussed.

CO2 emission trading within the European Union and Annex B countries: the cement industry case

The cement industry is the third largest carbon emitting industrial sector in the EU. This article presents the foreseeable technological evolution of the cement industry under business as usual circumstances, and examines the effects on the sector of carbon trading. For those purposes a global dynamic simulation model of the cement industry (CEMSIM) has been developed. The model is composed of a series of interconnected modules on cement consumption and production, international trade and capacity planning. This study quantifies the benefits achieved from emission trading in different markets (EU15, EU27 and Annex B), derived both from the revenues of emission trading, and from the lower compliance costs. The magnitude of the potential carbon leakage effect is also assessed.

CZSi結晶成長における3次元総合伝熱解析モデルの構築(オーガナイズドセッション4 材料創成プロセスと熱工学)

CZSi結晶成長における3次元総合伝熱解析モデルの構築(オーガナイズドセッション4 材料創成プロセスと熱工学)

Alternative U.S. and EU Sugar Trade Liberalization Policies and Their Implications

This study analyzes the impacts of alternative trade liberalization policies in the United States and the European Union (EU) on the U.S. sugar industry. A global sugar policy simulation model was used for this analysis. The study results indicate that the U.S. sugar industry may be able to survive if both the United States and the EU liberalize their sugar trade. However, if only the United States eliminates its sugar programs, all U.S. sugarproducing regions would be threatened.

The equatorial counter electrojet: Part of a worldwide current system?

The method of natural orthogonal components was applied to the ground geomagnetic data in the Central Asian sector (72–83°E), during the summer months of 1995, in an attempt to identify additional current systems that are superposed on the normal Sq current vortex and related to the equatorial counter electrojet (CEJ). The principal components, when examined in equivalent current representation, provide useful insights into the behavior of ionospheric current systems on different days. Statistical analyses performed in the present work suggest a possible relationship between the CEJ field and the noontime D variation observed at low latitudes. The results are in conformity with an earlier global simulation model.

Hierarchical simulation of complex production systems by coupling of models

The simulation of production systems usually requires rather detailed data, concerning the duration of the modelled activities, which determine the quality and reliability of simulation results. Application in industry has shown that these data are usually available for manufacturing. However, for non-manufacturing tasks, only rough data are available as expert guesses. Therefore, in order to simulate complex production systems which include manufacturing functions as well as pre- and post-manufacturing functions, it is often necessary to combine simulation models with different levels of detail. Therefore, an adequate approach is needed in order to avoid inconsistencies in results. Such inconsistencies may be connected with different levels of detail and occur if i.e. a highly detailed manufacturing model is combined with a more global simulation model for the winding-up of customer orders. The solution until now has been to define a simulation model with only one unique level of detail. If highly specific results are needed, the user is forced to build a very detailed model of the whole production system. Often, this turns out to be either impossible or connected with too much effort. If more global models are used instead, the obtained results may be insufficient to render an answer to the user's questions. At the ifab-Institute of the University of Karlsruhe, a new simulation tool OSim, which allows for the integration of variously detailed submodels into an overall global model of the investigated production system, is under development. The consistency of different models is guaranteed by a specific method of coupling the models. In this hierarchical way, the global simulation model can be combined with various submodels which contain more detailed processes. These detailed processes are then synchronised with the processes of the global model. For this purpose, the global model initiates an underlying process which then delivers its result to the global process. This combination of variously detailed models can be extended hierarchically. Following the description of this new simulation concept, a practical example for application will be given. This example is derived from an aluminium factory. It concerns the simulation of the overall winding-up of customer orders with their underlying manufacturing processes. The consistency of this simulation approach will be demonstrated by evaluating logistical key data at various levels of detail.

Trade and Environment: Bargaining Outcomes from Linked Negotiations

Some recent literature has explored physical and policy linkages between trade and the environment. This paper explores linkage through leverage in bargaining, whereby developed countries can use trade threats to achieve improved developing‐country environmental management, while developing countries can use environmental concessions to achieve trade discipline in developed countries. A global numerical simulation model is used to compute bargaining outcomes from linked trade and environment negotiations. Results indicate joint gains from expanding the trade bargaining set to include the environment. However, compared with bargaining with cash side‐payments, linked negotiations on policy instruments provide significantly inferior outcomes for developing countries.

A Modelling Approach to Global Nitrate Leaching Caused by Anthropogenic Fertilisation

Water quality associated with nitrate (NO3−) leaching from agricultural soils is an important environmental issue. This paper describes a new modelling approach to quantitatively evaluate the effect of the use of fertilisers on global nitrate leaching. A global process-based simulation model was previously developed for the nitrogen cycle in terrestrial ecosystems, in which soil inorganic nitrogen in the form of ammonium (NH4+) and NO3− was considered. After introducing data on world fertiliser consumption (FAO, 1995) into the steady-state model, the extent of disturbance to the nitrogen cycle caused by fertilisation was calculated. Although fertilisation resulted in an annual increase in net primary production (NPP, represented as carbon) of 18 Gtyear−1, NO3− leaching and gaseous losses of nitrogen oxides and ammonia were also accelerated. Most regions with heavy fertiliser application (over 100kgha−1year−1) showed a high annual leaching load equal to or more than 20kgha−1year−1. About 2.5% of the land area occupied by terrestrial ecosystems suffered a serious leaching load of more than 30kgha−1year−1. Of the total amount of applied fertilisers (138Tgyear−1) 19% was lost to NO3− leaching, 8% to gaseous ammonia, and 3% to gaseous nitrogen oxides. The rest was assumed to be fixed in the ecosystems through vegetation uptake.

Development of a global MHD simulation model for the S-M-I coupling process in the substorm prediction program at CRL

A global magnetohydrodynamic (MHD) model for the solar wind-magnetosphere-ionosphere (S-M-I) coupling process is developed as an essential tool of space weather prediction. Some examples of model outputs are shown to evaluate the model capability. The result for northward interplanetary magnetic field (IMF) input clearly shows the formation of lobe and merging cells. The transient solution after the southward turning of the IMF shows a new interpretation for the growth phase of the substorm.

A numerical study of solar wind—magnetosphere interaction for northward interplanetary magnetic field

The solar wind‐magnetosphere interaction for northward interplanetary magnetic field (IMF) is studied using a newly developed three‐dimensional adaptive mesh refinement (AMR) global MHD simulation model. The simulations show that for north‐ward IMF the magnetosphere is essentially closed. Reconnection between the IMF and magnetospheric field is limited to finite regions near the cusps. When the reconnection process forms newly closed magnetic field lines on the day side, the solar wind plasma trapped on these reconnected magnetic field lines becomes part of the low‐latitude boundary layer (LLBL) plasma and it convects to the nightside along the magnetopause. The last closed magnetic field line marks the topological boundary of the magnetospheric domain. When the last closed magnetic field line disconnects at the cusps and reconnects to the IMF, its plasma content becomes part of the solar wind. Plasma convection in the outer magnetosphere does not directly contribute to the reconnection process. On the dayside the topological boundary between the solar wind and the magnetosphere is located at the inner edge of the magnetopause current layer. At the same time, multiple current layers are observed in the high‐altitude cusp region. Our convergence study and diagnostic analysis indicate that the details of the diffusion and the viscous interaction do not play a significant role in controlling the large‐scale configuration of the simulated magnetosphere. It is sufficient that these dissipation mechanisms exist in the simulations. In our series of simulations the length of the magnetotail is primarily determined by the balance between the boundary layer driving forces and the drag forces. With a parametric study, we find that the tail length is proportional to the magnetosheath plasma beta near the magnetopause at local noon. A higher solar wind density, weaker IMF, and larger solar wind Mach number results in a longer tail. On the nightside downstream of the last closed magnetic field line the plasma characteristics are similar to that in the magnetotail, posing an observational challenge for identification of the topological status of the corresponding field lines.